The term “Qui tam” comes from a Latin phrase “qui tam pro domino rege quam pro se ipso in hac parte sequitur”, which essentially means "he who sues in this matter for the king as well as for himself." This phrase is used for cases in which a person can sue on behalf of the government. Qui Tam cases are also known as whistleblower cases.
"Qui Tam" has been around since thee Roman empire. It has been said that Roman prosecutions were initiated by private citizens and then later it became common-place for those citizens to receive a portion of the property previously owned by the criminal as a reward. Not only did the Romans have Qui Tam, but England also had such provisions. King Edward II once offered a portion of the recovery to a citizen after they successfully sued government officials who were moonlighting as wine merchants.
In the United States, the False Claims Act was introduced in 1863—during the time of the Civil War. The issue arose when contractors would sell faulty supplies, ammunition, animals in ill health, and rancid food rations to the Union Army. Under the False Claims Act, there is a qui tam provision which allows citizens to file a lawsuit against a business in behalf of the U.S. government.
In qui tam, a person who files suit is known as a "relator" and will receive a partial sum of the recovery. Someone who is employed by a business that is defrauding the government and files a Qui Tam suit is known as a whistleblower. The U.S. government has passed laws that protect Whistleblowers from retaliation from their employer once they file suit. Though some countries have since done away with qui tam laws, the United States continues to file qui tam suits under the False Claims Act.